What is CVE-2016-6391?

CVE-2016-6391 is a high-severity vulnerability in Cisco iOS, classified under CWE-399. CVSS score: 7.5/10. Published 2016-10-05.

How severe is CVE-2016-6391?

High severity. CVSS v3 base score is 7.5 out of 10.

Vulnerability in Cisco iOS

CVE-2016-6391

Cisco IOS 12.2 and 15.0 through 15.3 allows remote attackers to cause a denial of service (traffic-processing outage) via a crafted series of Common Industrial Protocol (CIP) requests, aka Bug ID CSCur69036.

Published 2016-10-05 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.019 (79.4th percentile), scored 2026-10-02.

Low probability of exploitation in the next 30 days, but still tracked. 79th percentile — 79.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.019 · newest: 0.019 · change: 0.000

Affected products

Cisco iOS — versions 12.2(55)se, 15.0(2)eb, 12.2(50)se2

Weakness classification (CWE)

CWE-399

References

www.securitytracker.com/id/1036914 (vdb-entry)
www.securityfocus.com/bid/93197 (vdb-entry)
tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20160928… (vendor-advisory, Vendor Advisory)

Frequently asked questions

What is CVE-2016-6391?: CVE-2016-6391 is a high-severity vulnerability in Cisco iOS, classified under CWE-399. CVSS score: 7.5/10. Published 2016-10-05.
How severe is CVE-2016-6391?: High severity. CVSS v3 base score is 7.5 out of 10.